Field of the Invention
The present invention relates to a method of controlling a target speed of a rotating member used in an image forming apparatus.
Description of the Related Art
An image forming apparatus that forms a mixed-color image primary transfers a toner image formed on a photosensitive drum to an intermediate transfer belt, and also secondary transfers the toner image from the intermediate transfer belt to a sheet. When thick paper having a larger grammage than normal paper is supplied to a secondary transfer unit as a sheet, a load put on an intermediate transfer belt changes, and a shock image may occur in a primary transfer unit. Such a shock image easily occurs in an image forming apparatus that has a multicolor mode and a monocolor mode and causes an intermediate transfer belt to separate from a plurality of photosensitive drums that form toner images of colors other than black in the monocolor mode. In the multicolor mode, there tends not to be an influence of a variation of load because a plurality of photosensitive drums are in contact with the intermediate transfer belt, but, in the monocolor mode, because only the photosensitive drum for black is in contact with the intermediate transfer belt, there tends to be an influence of a variation of load. Japanese Patent Laid-Open No. 2009-294312 recites reducing shock images by arranging a contacting member that nips the intermediate transfer belt between a photosensitive drum for black and a photosensitive drum for cyan, and continuously applying a load to the intermediate transfer belt by the contacting member.
However, in accordance with Japanese Patent Laid-Open No. 2009-294312, a dedicated contacting member for reducing shock images is necessary, leading to increased size and complexity of the image forming apparatus.